1. Field of the Invention
The present invention relates to a security door and a method of manufacturing a security door.
2. Description of the Prior Art
With the rise of anxiety concerning both personal safety and the security of property, the use of security doors has become increasingly commonplace. Conventional security doors are formed of rectangular frames of heavy metal tubing, often drawn and rolled steel having a thickness of about 0.090 inches. The steel tubing is formed to create upright stile members and upper and lower transverse rail members extending between the stile members. To create security, a grid of metal bars is provided across the rectangular opening defined between the stile and rail members. Some of these metal bars extend parallel to the stiles and are anchored to the transverse rail members at the top and bottom of the door. Other metal security bars are oriented perpendicular to the door stiles and are secured thereto.
In some cases additional decorative and angular metal bars are provided as an adjunct to the rectilinear grid that functions to provide the door with a high level of security. Quite often a security door is also provided with a screen mesh to exclude  invasion. Security doors are mounted in gate openings or in buildings in surrounding metal frames that are firmly secured in the doorway to be protected.
The conventional fabrication of security doors is both expensive and time consuming. Specifically, the metal security bars forming the rectilinear grillwork are at present secured to the elements or segments of the surrounding rectangular frame forming the door by means of arc welding. The process of arc welding is expensive and time consuming. Furthermore, arc welding requires a considerable amount of skill to create a sound weld. Therefore, it is necessary to employ factory workers with a high level of welding skill and experience in order to create the arc welds necessary in the fabrication of security doors. As an alternative to manual welding, robotic welding machines can be used. However, such robotic welding machines require major capital investments and drastically increase the overhead expenses necessary for security door fabrication.